The present invention is directed to a motion picture film wherein a layer containing a colorless, transparent ultra-violet light sensitive soundtrack is provided on one side of the film. The soundtrack covers the whole of either the front or back of the film and may be either variable density or vairable area type. The present invention is further directed to the use of a second emulsion to record a soundtrack on a film and the subsequent development thereof to produce a soundtrack which is substantially colorless and transparent to visible light, but fluoresces in the visible light spectrum when exposed to ultra-violet light.
Generally, in the prior art it has become standard procedure to provide a magnetic or optical recording track on the edge of a film adjacent the image when producing sound in motion pictures. However, this system is quite cumbersome since the provision of the soundtrack is an operation that is separate from the recording and developing operation. The width of the track, on the other hand, is a further limiting factor since it can only be on an area not covered by the photographic image, and thus must be very narrow due to the width of the film. Further, when utilizing narrow films such as those that have become quite popular for amateur movie makers, e.g., the "Super-8" films, there is not sufficient space on the film to provide a reasonable soundtrack which has good signal to noise ratio, frequency response and high information density. The present invention, on the other hand, provides a film and a method of using such film that admits of recording the sound on the full width of a film, especially on 8-millimeter film, and thus provides improved reproduction of the sound.
In U.S. Pat. No. 3,379,095 it was suggested that a filmstrip have the sound recording over the picture thereof. However, in the method suggested therein, a complex light-dividing system was necessary in order to provide both sound and image. Further, the materials utilized therein, although being transparent to visible light, were opaque to infra-red radiation and thus required the light-splitting techniques. The present invention, on the other hand, overcomes the expensive additional equipment required by such a system. These infra-red opaque coatings have to be placed on the film after the development thereof and do not appear to be applicable to almost simultaneous picture and sound recording. Thus, the process of the patent requires two steps to complete the recordings and requires additional equipment expenditure.
Further it is known to use various light systems, e.g. the system shown in U.S. Pat. No. 1,928,329 to Oswald et al, and U.S. Pat. Nos. 3,508,015 and 3,522,388 to Miller. However, these systems apparently do not recognize the possibility of recording both sound and images on the same film. The patent to Oswald uses a black and white film and visible light through a lens to provide the sound system while the patents to Miller utilize light emitting diodes of varying types. The systems thus suffer from the same lack of ease of good sound reproduction present in the magnetic strip type of sound recording.
Further, the art generally accomplishes multiple sound source effects by using separate, but synchronously run, film strips or magnetic tape. These systems present serious technical problems such as maintaining both sound and film image synchronization between the two separately run systems. This film may be of the standard 16mm, 35 or 70mm size. There is at present usually only room for one channel of sound on the rebate edge next to the image area of these commercial films. In the present invention and use, one or a plurality of soundtracks containing a transparent, substantially colorless ultra-violet fluorescent material are superimposed over the actual image area. One ultra-violet soundtrack exciter source may serve to energize, or cause to fluoresce all of the soundtracks, but each track must be read out by a separate photosensitive cell. Instead of having one soundtrack layer covering the entire area of the film, where plurality of soundtracks are contemplated, a number of soundtracks in strips across the surface of the film may be employed.
Thus, it is an object of the present invention to provide a film which may be first exposed to visible light to produce a photographic image and then almost simultaneously exposed to infra-red radiation or other selected portion of the spectrum to produce a soundtrack on the exposed film.
A further object of the present invention is to provide a finished film that has sound recording on the full width thereof and requires only a minimum of extra equipment to reproduce this sound.
Another object of the present invention is the provision of a high gain, high signal to noise ratio, variable density or variable area soundtrack.
It is an even further object to provide a simple method of reproducing sound on motion picture film which admits of recording by amateur photographers.
A further object of the invention is to provide means for the recording of multiplicity of synchronized soundtracks or channels on a single motion picture film release print and thus create, in the theatre, sterophonic or quadraphonic sound effects.
A still further object of the invention is to provide retrieval instructions on film to be used in automatic information retrieval systems, the filing instructions being placed over the useable image area of microchips and the like in a second emulsion which develops to become a transparent, colorless, ultra-violet, fluorescent material, and thus retrieval instructions do not obscure or use space that would otherwise be available for the recording and storage of other data.